This invention relates to a swab for collecting cell samples, and in particular to such a swab for use in collecting samples from the male urethra.
In order to diagnose certain urinary tract or genital diseases or to perform certain types of DNA testing, it is necessary to collect cell samples from the patient's urethra. This process has inherent difficulties with respect to males due to the small size of the urethra and the sensitivity surrounding its opening. First of all the probe end of the swab shaft must be small enough that when covered with the fiber tip that is used to capture cells it will fit comfortably in the urethra. At the same time the handle at the other end of the swab shaft must be sufficiently large to allow it to be firmly gripped. In addition, the swab shaft must be ductile enough so that it will not break and yet be stiff enough that it will not flex excessively during use.
This has been accomplished in the past with a two piece swab shaft. A hollow cylindrical handle has a smaller diameter stainless steel probe inserted into one end. The probe is heat-sealed to the handle. A fiber tip is then attached to the end of the probe. In order to prevent contamination of the collected cells during transportation to the laboratory, a swab of this type is partially inserted into a specimen tube and the protruding portion of the handle is broken off. The handle is scored to provide for breakage at the desired point. In the past this has been accomplished by rotating the handle under a blade.
Because of the cost of the stainless steel probe and the amount of hand assembly work, the prior art swabs are relatively expensive. In addition, carbon in the stainless steel probe may affect the results of DNA testing of samples collected with the swab.
The subject invention overcomes the foregoing problems associated with the prior art swabs by providing a unitary elongate glass filled nylon shaft which has a constant diameter circular cross-sectioned handle at one end and a tapered circular cross-sectioned probe at the other end. The shaft is between 5 and 20 percent fiberglass by volume and preferably is 10 percent fiberglass by volume. A fiber tip is located at the end of the probe to collect cell samples.
Preferably the probe covers approximately 25 percent of the overall length of the shaft and the diameter of the end of the probe is approximately one-third of the diameter of the handle. In the preferred embodiment, the handle has a diameter of approximately 0.100 inches and the end of the probe has a diameter of approximately 0.035 inches. The probe is made by injection molding and a score line is formed in the handle approximately at the midpoint of the shaft, as part of the molding process.
As a result of its shape and material, the subject swab provides similar size, strength and stiffness characteristics as the prior art two piece swabs at far less cost and with an inert probe.
The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the accompanying drawings.